• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.8
• /
• pp.879-886
• /
• 2012

The ultrasonic horn used for bonding of flip chip has been designed to vibrate at a natural frequency. The ultrasonic horn must be manufactured accurately in physical terms, because the small change of mechanical properties may result in the significant change of natural frequency. Therefore, tight tolerance is inevitable to keep the natural frequency in acceptable range. However, since tightening of the tolerance increases the manufacturing cost significantly, trade-off between the cost and accuracy is necessary. In this research, an attempt was made to design the ultra sonic horn within acceptable natural frequency while the manufacturing cost was kept as low as possible. For this purpose, among the 18 tolerances of physical terms of the ultrasonic horn, the most important 4 factors were selected using Taguchi method. The equation to relate those main factors and the natural frequency was made using response surface method. Finally, optimal design scheme for minimum manufacturing cost without a loss of performance was determined using SQP method.

• Korea Journal of Hospital Management
• /
• v.19 no.2
• /
• pp.1-11
• /
• 2014

The purpose of this study is to investigate awareness on medical insurance on the caregivers cost for hospital administrative staff and to provide the basic data for realization of legislation. The subjects were caregivers living in Busan, the survey was conducted from February 18 to March 9, 2013, 283 except for 17 copies of non-response and error response among a total of 300 questionnaires were analyzed. As a result, To improve the quality of care services, there were 51.8% of refresher training needs in refresher training items, 72.7% in favor of premiums increases in health insurance details, as for health insurance coverage subjects, patients' income were 32.0%, copayment for caregivers cost was 20.0%, which was 42.3%. Refresher training item, premiums increases, health insurance applied subjects, variables for copayment for care fee were related to medical insurance on the caregivers cost. On legislation on the medical insurance, systematic and standardized criteria should be provided to provide standardized curriculum for caregivers, to relieve patients and guardians of economic burden for caregivers cost and offer the stability of the cost.

• Journal of the Korea Convergence Society
• /
• v.13 no.1
• /
• pp.283-295
• /
• 2022

This study attempts to explore factors that influence the perception of importance of information security. Three possible exogenous variables including perceived certainty of punishment, perceived response cost, and acquiescense are suggested that are based on the protectiom motivation theory. As a result, we found followings. First, The perceived punishment certainty has a significant effect on the perceived importance of information security. Also, it influences a negative effect on acquiescence. Second, the response cost has a negative effect on the perceived importance of information security. In addition, the response cost positively effects on acquiescence. Finally, acquiescence negatively influences on the perceived importance of information security. The results show that, in order to increase the perceived importance of information security among employees, it is necessary to make them aware that a security violation can result in certain punishment. At the same time, organizations should also attempt to remove major obstacles accompanying security behaviors of employees. Finally, organizations encourage open communication relating to information security among employees.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.6
• /
• pp.422-428
• /
• 2011

Optimal reliability indices were found by optimizing life cycle cost(LCC) of pier type quay walls. Failure probability of pier and shore bridge were calculated by response surface method. Then, they were used to obtain recovery cost after damage. Costs for initial construction and maintenance were also considered in finding optimal reliability indices. Target reliability indices which may be used in reliability based design were suggested by numerical examples under seismic load and ship load.

• Journal of Information Processing Systems
• /
• v.10 no.4
• /
• pp.628-645
• /
• 2014

In past few years, distributed hash table (DHT)-based P2P systems have been proven to be a promising way to manage decentralized index information and provide efficient lookup services. However, the skewness of users' preferences regarding keywords contained in a multi-keyword query causes a query load imbalance that combines both routing and response load. This imbalance means long file retrieval latency that negatively influences the overall system performance. Although index replication has a great potential for alleviating this problem, existing schemes did not explicitly address it or incurred high cost. To overcome this issue, we propose, in this paper, an integrated solution that consists of three replication schemes to alleviate query load imbalance while minimizing the cost. The first scheme is an active index replication that is used in order to decrease routing load in the system and to distribute response load of an index among peers that store replicas of the index. The second scheme is a proactive pointer replication that places location information of each index to a predetermined number of peers for reducing maintenance cost between the index and its replicas. The third scheme is a passive index replication that guarantees the maximum query load of peers. The result of simulations indicates that the proposed schemes can help alleviate the query load imbalance of peers. Moreover, it was found by comparison that our schemes are more cost-effective on placing replicas than PCache and EAD.

• Advances in concrete construction
• /
• v.11 no.4
• /
• pp.285-298
• /
• 2021

This study focused on experimental evaluation of mechanical properties of pervious concrete mixtures with the aim of achieving higher values of strength while considering the associated costs. The effectiveness of key parameters, including cement content, water to cement ratio (W/C), aggregate to cement ratio (A/C), and sand replacement was statistically analyzed using paired-samples t-test, Taguchi method and one-way ANOVA. Taguchi analysis determined that in general, the role of W/C was more significant in increasing strength, both compressive and flexural, than cement content and A/C. It was found that increase in replacing percent of coarse aggregate with sand could undermine specimens to percolate water, though one-way ANOVA analysis determined statistically significant increases in values of strength of mixtures. Cost analysis revealed that higher strengths did not necessarily correspond to higher costs; in addition, increasing the cement content was not an appropriate scenario to optimize both strength and cost. In order to obtain the optimal values, response surface method (RSM) was carried out. RSM optimization helped to find out that W/C of 0.40, A/C of 4.0, cement content of about 330 kg/m3 and replacing about 12% of coarse aggregate with sand could result in the best values for strength and cost while maintaining adequate permeability.

• Wind and Structures
• /
• v.21 no.6
• /
• pp.597-607
• /
• 2015

With an increasing demand of a renewable energy, new offshore wind turbine farms are being planned in some parts of the world. Foundation installation asks a significant cost of the total budget of offshore wind turbine (OWT) projects. Hence, a cost reduction from foundation parts is a key element when a cost-efficient designing of OWT budget. Mono-piles have been largely used, accounting about 78% of existing OWT foundations, because they are considered as a most economical alternative with a relatively shallow-water, less than 30 m of seawater depth. OWT design standards such as IEC, GL, DNV, API, and Eurocode are being developed in a form of reliability based limit state design method. In this paper, reliability analysis using the response surface method (RSM) and numerical simulation technique for an OWT mono-pile foundation were performed to investigate the sensitivities of mono-pile design parameters, and to find practical implications of RSM reliability analysis.

• Structural Engineering and Mechanics
• /
• v.67 no.6
• /
• pp.671-682
• /
• 2018

The effect of earthquake induced torsion, due to mass eccentricities, is investigated with the objective of providing practical design guidelines for minimizing the torsional response of building structures. Current code provisions recommend performing three dimensional static or dynamic analyses, which involve shifting the centers of the floor masses from their nominal positions to what is called an accidental eccentricity. This procedure however may significantly increase the design cost of multistory buildings, due to the numerous possible spatial combinations of mass eccentricities and it is doubtful whether such a cost would be justifiable. This paper addresses this issue on a theoretical basis and investigates the torsional response of asymmetric multistory buildings in relation to their behavior when all floor masses lie on the same vertical line. This approach provides an insight on the overall seismic response of buildings and reveals how the torsional response of a structure is influenced by an arbitrary spatial combination of mass eccentricities. It also provides practical guidelines of how a structural configuration may be designed to sustain minor torsion, which is the main objective of any practicing engineer. A parametric study is presented on 9-story common building types having a mixed-type lateral load resisting system (frames, walls, coupled wall bents) and representative heightwise variations of accidental eccentricities.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1999.04a
• /
• pp.178-185
• /
• 1999

Minimum life-cycle cost helps to evaluate cost effectiveness of base-isolated bridges under specific condition. Life-cycle cost mainly consists of the initial construction cost and the expected damage cost. Damage cost estimation needs proper model of input ground motion failure probability evaluation method and limit states definition. We model the input ground motion as spectral density function compatible with the response spectra defined at each seismicity and site condition. Spectrum analysis and crossing theory is suitable for reseating calculation of failure probabilities in the process of cost minimization. Limit states of base-isolated bridges re defined for superstructure isolator and pier respectively The method is applied to both base-isolated bridges and conventional bridges under the same conditions to investigate cost effectiveness of base isolation in low and moderate seismic region. the results show that base-isolation of bridges are more effective in low and moderate seismic region and that the site effects on the economical efficiency may not be negligible in such a region.

• International Journal of Automotive Technology
• /
• v.4 no.4
• /
• pp.193-201
• /
• 2003

The problem of brake judder is typically caused by defects of quality manufacturing. DFSS (Design for six sigma) is a design process for quality improvement. DFSS will result in more improved but less expensive quality products. This paper presents an implementation of DFSS for quality improvement of the brake judder of heavy-duty trucks. Carrying out 5 steps of DFSS, the major reasons for defects of quality are found. The numerical approximation of the brake system is derived by means of the response surface method. Its quality for brake judder is improved by using the sigma based robust design methodology. Results are compared between the conventional deterministic optimal design and the proposed sigma based robust design. The proposed one shows that manufacturing cost may increase as the quality level increase. The proposed one, however, is more economical in aspect of the overall cost since the probability of failure dramatically goes down.